Compiling for both i386 and ARM

On Debian-based systems, the packages gcc-multilib and gcc-arm-linux-gnueabihf have conflicts. A workaround:

• Install gcc-arm-linux-gnueabihf and gcc-6-multilib, which don't conflict.
• Create a directory /usr/include/i386-linux-gnu and manually make a symlink

ln -s ../x86_64-linux-gnu/asm /usr/include/i386-linux-gnu.